macos - 使 2 个相互矛盾的方法在 drawRect 中起作用

Question

我正在编写一个由 CGPoints 组成的应用程序构建元素。我有 2 个按钮:makeRectangle和 makeTriangle .对于构建/绘图阶段，我使用三种方法 矩形以及 的三种方法三角形内drawRect .

我的代码被困在 drawRect .在 if-else-statement每次按下按钮时，每种方法都会为前一个元素交换建筑/绘图方案。

如果我已经建立了矩形 然后我点击 makeTriangle按钮，我得到了新的三角形，但我的矩形变成了一个有一个未连接点的三角形。

是否有解决方法 否则我不应该使用 drawRect方法？

这是 drawRect 上的 SO 帖子主题:To drawRect or not to drawRect





元素声明:

enum Element {
    case point1(point: CGPoint)
    case point2(point: CGPoint)
    case point3(point: CGPoint)
    case point4(point: CGPoint)

    func coord() -> [CGPoint] {    
        switch self {  
        case .point1(let point): return [point]
        case .point2(let point): return [point]
        case .point3(let point): return [point]
        case .point4(let point): return [point]
        }
    }
    func buildQuadPath(path: CGMutablePath) {
        switch self {
        case .point1(let point): CGPathMoveToPoint(path, nil, point.x, point.y)
        case .point2(let point): CGPathAddLineToPoint(path, nil, point.x, point.y)
        case .point3(let point): CGPathAddLineToPoint(path, nil, point.x, point.y)
        case .point4(let point): CGPathAddLineToPoint(path, nil, point.x, point.y)
        CGPathCloseSubpath(path)
        }
    }
    func buildTriPath(path: CGMutablePath) {
        switch self {
        case .point1(let point): CGPathMoveToPoint(path, nil, point.x, point.y)
        case .point2(let point): CGPathAddLineToPoint(path, nil, point.x, point.y)
        case .point3(let point): CGPathAddLineToPoint(path, nil, point.x, point.y)
        default:
        CGPathCloseSubpath(path)
        }
    }
}

构建和绘制三角形和矩形的方法:

func buildTriPath() -> CGMutablePath {
    let path = CGPathCreateMutable()
    _ = array.map { $0.buildTriPath(path) }
    return path
}
func drawTriPath() {
    let path = buildTriPath()
    GraphicsState {
        CGContextAddPath(self.currentContext, path)
        CGContextStrokePath(self.currentContext)
    }
}
func drawTriFill() {
    let fill = buildTriPath()
    GraphicsState {
        CGContextAddPath(self.currentContext, fill)
        CGContextFillPath(self.currentContext)
    }
}

//////////////////////////////////////////////////////

func buildQuadPath() -> CGMutablePath {
    let path = CGPathCreateMutable()
    _ = array.map { $0.buildQuadPath(path) }
    return path
}
func drawQuadPath() {
    let path = buildQuadPath()
    GraphicsState {
        CGContextAddPath(self.currentContext, path)
        CGContextStrokePath(self.currentContext)
    }
}
func drawQuadFill() {
    let fill = buildQuadPath()
    GraphicsState {
        CGContextAddPath(self.currentContext, fill)
        CGContextFillPath(self.currentContext)
    }
}

两个变量有助于确定按钮是否被按下:

var squareB: Int = 0
var triangleB: Int = 0

@IBAction func makeTriangle(sender: AnyObject?) {
    ....................
    ....................
    triangleB += 1
    squareB = 0
}
@IBAction func makeRectangle(sender: AnyObject?) {
    ....................
    ....................
    triangleB = 0
    squareB += 1
}

drawRect方法:

override func drawRect(dirtyRect: NSRect) {
    super.drawRect(dirtyRect)

    drawBG()
    GraphicsState { self.drawMyPoints() }

    if squareB >= 1 && triangleB == 0 {
        buildQuadPath()
        drawQuadPath()
        drawQuadFill()
        needsDisplay = true
    }
    else if triangleB >= 1 && squareB == 0 {
        buildTriPath()
        drawTriPath()
        drawTriFill()
        needsDisplay = true
    }
    drawBorder()
}

...最后是 Context.swift文件:

import Cocoa
import CoreGraphics

extension NSView {

    var currentContext : CGContext? {

        get {

            let unsafeContextPointer = NSGraphicsContext.currentContext()?.graphicsPort

            if let contextPointer = unsafeContextPointer {
            let opaquePointer = COpaquePointer(contextPointer)
            let context: CGContextRef = Unmanaged.fromOpaque(opaquePointer).takeUnretainedValue()
            return context }
            else { return nil }
        }
    }

    func GraphicsState(drawStuff: () -> Void) {
        CGContextSaveGState(currentContext)
        drawStuff()
        CGContextRestoreGState(currentContext)
    }
}

//the end of code

Answer 1

if (makeTriangle != nil) {和 if (makeRectangle != nil) {没有多大意义。根据您的评论，makerRectangle和 makeTriangle是按钮。通过你的语句，你正在检查它们的存在——我们可以假设它们总是存在——第一个 if 子句将始终被执行。

你想要的是:创建将由按钮执行的方法。每个方法都将设置 bool 值的组合或单个枚举值，然后通过调用 setNeedsDisplay() 告诉 View 重绘.